In 2015, 40,000 delegates flew into Paris from 196 nations – ­carbon footprint anyone? The ­result was an agreement that legally committed nobody to any carbon dioxide emission ­reductions. Who can ever forget the last-minute panic to reach an agreement, any agreement?

Its goal of a maximum two degrees Celsius increase in ­global temperatures above pre-industrial levels is estimated to have a global cost of US$17 trillion by 2040 and would require carbon dioxide reductions about 100 times greater than those pledged in Paris.

Trump, with a businessman’s eye for detail, looked at the figures and realised there was nothing there except a lot of economic pain for his country, should the promises be met, with no actual benefit to anyone in the developed world.

The US is already streets ahead of many developed ­nations in reducing its carbon footprint. This is thanks mainly to the technological developments we would expect of an ­advanced nation, despite, not because of, government interference: efficiency in obtaining, generating and using fossil fuel-based power, better waste management and reductions in ­pollution.

G. Bailey, Ta Kwu Ling

It is not easy to be a top-class e-sports player

The popularity of e-sports is growing and there are now even international competitions. It was good to see young Hongkongers in a team that reached the finals of the League of ­Legends tournament at the ­e-sports festival held here earlier this month.

More youngsters from the city now hope to have a career as professional e-gamers, but they have to be realistic.

You are unlikely to earn enough to get by unless you are a top professional player and to get to that level requires a lot of talent and dedication.

Fung Siu-chung, Hang Hau

Smartphones can become addictive

Of course, these devices are convenient and can help us in our lives but, if they are misused, they can be harmful.

They help us to keep up with current affairs, search for information on any subject and take photos of special occasions with relatives and friends.

Tech-savvy teenagers can improve their efficiency in their studies and, in the workplace, computers are an essential part of any project and, at university, any type of research.

However, some people can come to rely too much on their smartphone, to the point where they feel they cannot do without it. They hold it all the time and look at it constantly.

In fact, they are so reliant that they would panic if they had to go a day without their mobile; if they could not text friends, play computer games or surf the internet.

Overdependence on these devices can, in extreme cases, lead to addiction, which is damaging to a person’s health, physically and psychologically.

They will suffer from headaches and eye strain from looking at the screen for so long and feel tired all the time. And they could have neck strain and chronic pain in their wrists and elbows. Many of these addicts lose touch with the real world, including friends and family.

People need to realise that moderation is the key. They should allocate a certain amount of time they will spend online and stick to that.

Kenny Tsang Pak-shing, Sha Tin

NGOs treating drug addicts need more help

The problem of teenage drug abuse is becoming more serious in Hong Kong. Some youngsters try these drugs because they mistakenly think this will help relieve stress. Others do so ­because they feel bored.

They do not appreciate the terrible risks they face and how drug addiction will have a ­devastating effect on their lives.

I appreciate the government’s efforts to deal with this problem and help teens who have been abusing illegal drugs. It has set up clinics for addicts, but it could do more. It needs to give NGOs, which were set up to support addicts, the funds they need to keep operating.

Parents must realise that this is a major problem. They need to keep the lines of communication open with their children so that, if they have emotional problems, they can talk freely.

Bryan Wong, Tseung Kwan O